The present invention generally relates to parallel-transmission flat cables equipped with connector units, and, more particularly, to a parallel-transmission flat cable that is equipped with a connector unit and has end portions at either end thereof. The end portions can be connected directly to the contacts of a mating connector.
Examples of conventional data transmission methods include a regular transmission method by which one wire is used for each set of data, and a parallel-transmission method by which a pair of wires are used for each set of data so as to simultaneously transmit a positive signal and a negative signal that is of the same size as the positive signal but are directed in the opposite direction from the positive signal. The parallel-transmission method is more advantageous than the regular transmission method in that signal transmission with less noise influence can be performed. Accordingly, the parallel-transmission method is being more and more widely employed in the fields that require high-speed signal transmission.
Conventionally, to parallel-transmit signals between two devices or between two locations within a device, a cable that has pairs of wires contained in a double-cover tube is employed. Such a cable has a connector at either end, and the connector has contacts incorporated therein.
However, with such a conventional cable quipped with connectors, there have been problems that the production costs of the cable and the connectors are high, and accordingly, the cable becomes expensive. Also, the cable is large in size, and is not suitable for connecting one location to another within a small device.
Furthermore, the pairs of wires and the contacts of the connector that is mounted and fixed onto a printed board are connected via the contacts of the connector unit provided on either end of the cable. Therefore, the connecting portions between the ends of the pairs of wires and the contacts of the connector at either end of the cable might adversely affect the parallel-transmission characteristics.